The purpose of this project is to determine whether epinephrine and its biosynthetic enzyme (phenylethanolamine N-methyltransferase) in the central nervous system play a major role in the development of the hypertension in the spontaneously hypertensive rat. While the role of epinephrine and PNMT in the adrenal gland has been studied quite extensively, such studies have not been extended to the brain. Results from our laboratory as well as the literature suggests that: (1) there is not a direct relationship between central epinephrine levels, PNMT activity an blood pressure. Inhibitors of PNMT have been found to be hypotensive agents, although evidence suggests that blood pressure reduction is not necessarily related to enzyme inhibition. Reduction of blood pressure by other hypotensive agents does not alter PNMT activity in brain.